This invention concerns a device for controlling and independent rocking of straightening and bending platforms.
To be more exact, the invention is applied to machines that form shaped iron rods for building work and, in particular, shaped stirrup-type rods for the steel reinforcement structures which are sunk in concrete to make reinforced concrete.
The bending-shaping machine according to the invention comprises a straightening assembly upstream of a bending-shaping assembly which is of a type having a disk, central contrast pin and offset beinding pin, for instance.
The bending-shaping machine to which the invention is applied is arranged so that the straightening assembly and bending-shaping assembly lie on independent platforms and the platform of the bending-shaping assembly can be oriented about a lengthwise axis which is substantially parallel to the axis of the passage of the rod to be bent and shaped and is positioned below that latter axis so as to leave the bending platform always free of anything which might obstruct the rod being bent.
The bending platform is that which holds, and on which lies, the bending assemblY and which supports the rod to be bent and shaped during the passage and bending of the rod.
Instead, the straightening platform is that which holds and supports the straightening assembly.
The rod which has to be bent and shaped may have a solid or hollow conformation and may have a smooth surface or have superficial modifications. It cross section may be oval, round, three-lobed, quandrangular, etc.
The rod which has to be bent and shaped will come almost always from a reel, and the straightening assembly will not only have to straighten the rod passing through but will also have to fix the twists which have been imparted to the rod during winding onto and unwinding from a reel.
An example of such straightening is disclosed in the document EP 87202107.6.
It should be borne in mind that rods being unwound from a bundle formed in the hot state on a reel comprise coils which have a difference in length between their inner and outer circumferences.
It is necessary to remember also that such bending-shaping machines can process rods of any size between diameters of 4 and 16 mm. or equivalent diameters.
In normal wound bundles having an average diameter of 1.2 meters a rod with a diameter of 16 mm. has a difference of more than 5 cms. between the lengths of the outer and inner circumferences of a coil.
This difference was not important in the past since the reinforcement rods consisted usually of mild steel of the type FE 33, for instance.
With modern high-strength steels of the type FE 50 and higher, for instance, the problems of the straightening and behaviour of the rods upstream of the straightening assembly have become very important for a successful outcome of the bending and shaping of the rod.
In the bending-shaping machines under discussion, the straightening platform on which the straightening assembly lies is independent of the bending platform on which the bending assembly lies and on which the bending and shaping and subsequently shearing of the rod are carried out.
In machines of this type, and in bending-shaping machines more generally, the adjustment of the rollers of the straightening assembly takes place automatically at the beginning of each wound bundle of rod, and the processing of the rod forming the bundle proceeds by using the same wound bundle as much as possible so as to be able to spread out over the greatest possible number of pieces the downtimes due to preparation of the machine when the type of rod has to be changed.
This means that during the processing of one wound bundle stirrups shaped in different ways and of different sizes or straight rods or bent rods of various types may be produced.
It also means that each type of stirrups or bent rod requires a preferred angular position of the bending platform.
Most of the shaped and bent pieces normally require the bending platform to be inclined in relation to the horizontal by a value between 15.degree. and 45.degree., advantageously about 30.degree..
In other words, if the type of straight or bent rod or stirrup to be produced is changed, the machine, within certain values, changes its trim and, in particular, its trim in relation to the horizontal of the bending platform.
As we said above, the bending assembly carries the bending action out as well as possible, in general and particular terms, if it is positioned at a determined angle to the horizontal.
This angle, which varies from 0.degree. (horizontal platform) to 100/150.degree. (inclined platform), depends on a plurality of factors, and the machine manufacturers normally determine it for each type or range of product during design work and then admit a greater or smaller range of angles.